To form a magnetic field, the field coil of an inductive sensor is supplied with AC voltage by a power circuit.
In inductive sensors in modern motor vehicles, the power circuit is present in the form of an H-shaped bridge connected to an electric source. The switches of the H-shaped bridge are controlled so as to circulate in the field coil an electric current circulating alternatively in one direction, then in the opposite direction.
So as to improve the reliability of the functioning of modern inductive sensors, it is known to provide a plurality of power circuits each comprising an H-shaped bridge. Said power circuits cannot be connected in parallel to the terminals of the electric source since this would be at risk of being short-circuited. Consequently, at any given moment, a single power circuit is active and connected to the field coil, the other power circuits then being passive and disconnected from said field coil.
If the power circuit connected to the field coil becomes faulty, it is disconnected from said field coil and another power circuit is connected to the field coil.
However, the detection of the fault of the power circuit connected to the field coil is not instantaneous. Consequently, no position measurement can be taken between the moment at which the power circuit connected to the field coil becomes faulty and the moment at which another power circuit is connected to the field coil.
It is understood that such an unavailability of the inductive sensor may prove bothersome if the position measurement taken by said inductive sensor is significant for the functioning of the motor vehicle.
In particular, the object of the invention is to solve this problem.